Melanocortins are a family of regulatory peptides which are formed by post-translational processing of pro-hormone pro-opiomelanocortin (POMC; 131 amino acids in length). POMC is processed into three classes of hormones; the melanocortins, including but not limited to α-MSH (melanocyte stimulating hormone), β-MSH and γ-MSH, adrenocorticotropin hormone (ACTH), various endorphins (e.g. lipotropin) (Cone, R. D. et al., Recent Prog. Horm. Res., 51:287-317 (1996); and Cone, R. D. et al., Ann. N.Y. Acad. Sci., 31:342-63 (1993)) and their peptide fragments. Melanocortins have been found in a wide variety of normal human tissues including the brain, adrenal, skin, testis, spleen, kidney, ovary, lung, thyroid, liver, colon, small intestine and pancreas (Tatro, J. B. et al., Endocrinol., 121:1900-7 (1987); Mountjoy, K. G. et al., Science, 257:1248-51 (1992); Chhajlani, V. et al., FEBS Lett., 309:417-20 (1992); Gantz, I. et al., J. Biol. Chem., 268:8246-50 (1993) and Gantz, I. et al., J. Biol. Chem., 268:15174-9 (1993)).
Melanocortin peptides have been shown to exhibit a wide variety of physiological activities including the control of behavior and memory, affecting neurotrophic and antipyretic properties, as well as affecting the modulation of the immune system. Aside from their well known effects on adrenal cortical functions (adrenocorticotropic hormone, ACTH) and on melanocytes (melanocyte stimulating hormone, MSH), melanocortins have also been shown to control the cardiovascular system, analgesia, thermoregulation and the release of other neurohumoral agents including prolactin, luteinizing hormone and biogenic amines (De Wied, D. et al., Methods Achiev. Exp. Pathol., 15:167-199 (1991); De Wied, D. et al., Physiol. Rev., 62:977-1059 (1982); Guber, K. A. et al., Am. J. Physiol. 257:R681-R94 (1989); Walker, J. M. et al., Science, 210:1247-9 (1980); Murphy, M. T. et al., Science, 221:192-3 (1983); Ellerkmann, E. et al., Endocrinol., 130:133-8 (1992) and Versteeg, D. H. G. et al., Life Sci., 38:835-40 (1986)).
It has also been shown that binding sites for melanocortins are distributed in many different tissue types including lachrymal and submandibular glands, pancreas, adipose, bladder, duodenum, spleen, brain and gonadal tissues as well as malignant melanoma tumors. Five melanocortin receptors (MC-R) have been characterized to date. These include melanocyte-specific receptor (MC1-R), corticoadrenal-specific ACTH receptor (MC2-R), melacortin-3 (MC3-R), melanocortin-4 (MC4-R) and melanocortin-5 receptor (MC5-R). All of the melanocortin receptors respond to the peptide hormone class of melanocyte stimulating hormones (MSH) (Cone, R. D. et al., Ann. N.Y. Acad. Sci., 680:342-63 (1993); and Cone, R. D. et al., Recent Prog. Horm. Res., 51:287-318 (1996)).
MC1-R, known in the art as Melanocyte Stimulating Hormone Receptor (MSH-R), Melanotropin Receptor or Melanocortin-1 Receptor, is a 315 amino acid transmembrane protein belonging to the family of G-Protein coupled receptors. MC1-R is a receptor for both MSH and ACTH. The activity of MC1-R is mediated by G-proteins which activate adenylate cyclase. MC1-R receptors are found in melanocytes and corticoadrenal tissue as well as various other tissues such as adrenal gland, leukocytes, lung, lymph node, ovary, testis, pituitary, placenta, spleen and uterus. MC2-R, also called Adrenocorticotropic Hormone Receptor (ACTH-R), is a 297 amino acid transmembrane protein found in melanocytes and the corticoadrenal tissue. MC2-R mediates the corticotrophic effect of ACTH. In humans, MC3-R is a 360 amino acid transmembrane protein found in brain tissue; in mice and rats MC3-R is a 323 amino acid transmembrane protein. MC4-R is a 332 amino acid transmembrane protein which is also expressed in brain as well as placental and gut tissues. MC5-R is a 325 amino acid transmembrane protein expressed in the adrenals, stomach, lung and spleen and very low levels in the brain. MC5-R is also expressed in the three layers of adrenal cortex, predominantly in the aldosterone-producing zona glomerulosa cells.
The five known melanocortin receptors differ, however, in their functions. For example, MC1-R is a G-protein coupled receptor that regulates pigmentation in response to α-MSH, a potent agonist of MC1-R. Agonism of the MC1-R receptor results in stimulation of the melanocytes which causes eumelanin and increases the risk for cancer of the skin. Agonism of MC1-R can also have neurological effects. Stimulation of MC2-R activity can result in carcinoma of adrenal tissue. Recent pharmacological confirmation has established that central MC4-R receptors are the prime mediators of the anorexic and orexigenic effects reported for melanocortin agonists and antagonists, respectively. The effects of agonism of the MC3-R and MC5-R are not yet known.
There has been great interest in melanocortin (MC-R) receptors as targets for the design of novel therapeutics to treat disorders of body weight such as obesity and cachexia. Both genetic and pharmacological evidence points toward central MC4-R receptors as the principal target (Giraudo, S. Q. et al., Brain Res., 809:302-6 (1998); Farooqi, I. S. et al., N.E. J. Med., 348:1085-95 (2003); MacNeil, D. J. et al., Euro. J. Pharm., 44:141-57 (2002); MacNeil, D. J. et al., Euro. J. Pharm., 450:93-109 (2002); Kask, A. et al., NeuroReport, 10:707-11 (1999); Huszer, D. et al., Cell, 131-41 (1997); Klebig, M. L. et al., Proc. Natl. Acad. Sci., 92:4728-32 (1995); Karbon, E. et al., Abstr. 19th Ann. Winter Neuropeptide Conf., (1998); Fan, W. et al., Nature, 385:165-8 (1997); Seely, R. J., Nature, 390:349 (1997); Comuzzie, A. G., Nat. Gen., 15:273-6 (1997); Chagnon, Y. C., Mol. Med., 3(10):663-73 (1997); WO 97/47316 (Lee et al., 1997); and Shutter, J. R., Gen. & Dev., 11:593-602 (1997)). Stimulation of the MC-4 receptor by its endogenous ligand, αMSH, produces a satiety signal. It is believed that by providing potent MC-4 receptor agonists, appetite might be suppressed and weight loss achieved.
The current progress with receptor-selective agonists and antagonists evidences the therapeutic potential of melanocortin receptor activation, particularly MC4-R.
Agonist, antagonist or other ligand compounds activating one or more melanocortin receptor would be useful for treating a wide variety of indications in a subject in need thereof or at risk thereof including acute and chronic inflammatory diseases such as general inflammation (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), inflammatory bowel disease (U.S. Pat. No. 6,713,487 (Yu et al., 2004)); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), brain inflammation (Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), sepsis (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); U.S. Pat. No. 6,713,487 (Yu et al., 2004); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)) and septic shock (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), diseases with an autoimmune component such as rheumatoid arthritis (U.S. Pat. No. 6,713,487 (Yu et al., 2004); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), gouty arthritis (Catania, A. et al., Pharm. Rev., 56:1-29 (2004); and Getting, S. J. et al., Curr. Opin. Investig. Drugs, 2:1064-9 (2001)), and multiple sclerosis (U.S. Pat. No. 6,713,487 (Yu et al., 2004)), metabolic diseases and medical conditions accompanied by weight gain such as obesity (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); U.S. Pat. No. 6,600,015 (Chen et al., 2003); Fehm, H. L. et al., J. Clin. Endo. & Metab., 86:1144-8 (2001); Hansen, M. J. et al., Brain Res., 1039:137-45 (2005); Ye, Z. et al., Peptides, 26:2017-25 (2005); Farooqi, I. S. et al., N.E. J Med., 348:1085-95 (2003); MacNeil, D. J. et al., Eu. J. Pharm., 44:141-57 (2002); MacNeil, D. J. et al., Euro. J. Pharm., 450:93-109 (2002); Kask, A. et al., NeuroReport, 10:707-11 (1999); Schwartz, M. W., J. Clin. Invest., 108:963-4 (2001); Gura, T., Science, 287:1738-40 (2000); Raffin-Sanson, M. L., Euro. J. Endo., 144:207-8 (2001); and Hamilton, B. S. et al., Obesity Res., 10:182-7 (2002)), feeding disorders (U.S. Pat. No. 6,720,324 (Marzabadi et al., 2004); Fehm, H. L. et al., J. Clin. Endo. & Metab., 86:1144-8 (2001); and Pontillo, J. et al., Bioorganic & Med. Chem. Ltrs., 15:2541-6 (2005)) and Prader-Willi Syndrome (GE, Y. et al., Brain Res., 957:42-5 (2002)), metabolic diseases and medical conditions accompanied by weight loss such as anorexia (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); and Wisse, B. R. et al., Endocrinology, 142:3292-301 (2001)), bulimia (U.S. Pat. No. 6,720,324 (Marzabadi et al., 2004)), AIDS wasting (Marsilje, T. H. et al., Bioorg. Med. Chem. Lett., 14:3721-5 (2004); and Markison, S. et al., Endocrinology, 146:2766-73 (2005)), cachexia (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); Lechan, R. M. et al., Endocrinology, 142:3288-91 (2001); and Pontillo, J. et al., Bioorganic & Med. Chem. Ltrs., 15:2541-6 (2005)), cancer cachexia (U.S. Pat. No. 6,639,123 (Van der Ploeg et al., 2003)) and wasting in frail elderly (U.S. Pat. No. 6,639,123 (Van der Ploeg et al., 2003)), diabetes (U.S. Pat. No. 6,713,487 (Yu et al., 2004)) and diabetalogical related conditions and complications of diabetes such as retinopathy (U.S. Pat. No. 6,525,019 (D'Amato, 2003), neoplastic proliferation (U.S. Pat. No. 6,713,487 (Yu et al., 2004)) such as skin cancer (Sturm, R. A., Melanoma Res., 12:405-16 (2002); and Bastiens, M. T. et al., Am. J. Hum. Genet., 68:884-94 (2001)), and prostate cancer (Luscombe, C. J. et al., British J. Cancer, 85:1504-9 (2001)), reproductive or sexual medical conditions such as endometriosis (U.S. Pat. No. 6,713,487 (Yu et al., 2004)) and uterine bleeding in women (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), sexual dysfunction (U.S. Pat. No. 6,720,324 (Marzabadi et al., 2004); Van der Ploeg, L. H. T. et al., PNAS, 99:11381-6 (2002), Molinoff, P. B. et al., Ann. N.Y. Acad. Sci., 994:96-102 (2003), and Hopps, C. V. et al., B.J.U. Int'l., 92:534-8 (2003)), erectile dysfunction ((U.S. Pat. No. 6,613,874 (Mazur et al., 2003); Diamond, L. E. et al., Urology, 65:755-9 (2005); Wessells, H. et al., Int'l. J. Impotence Res., 12:S74-9 (2000); Andersson, K-E. et al., Int'l. J. Impotence Res., 14:S82-S92 (2002); Bertolini, A. et. al., Sexual Behavior: Pharmacology and Biochemistry, Raven Press, NY, p 247-57 (1975); Wessells, H. et al., Neuroscience, 118:755-62 (2003); Wessells, H. et al., Urology, 56:641-6 (2000); Shadiack, A. M. et al., Soc. for Neuroscience Abst, (2003); Wessells, H. et al., J. Urology, 160:389-93 (1998); Rosen, R. C. et al., Int'l. J. Impotence Res., 16:135-42 (2004); and Wessells, H. et al., Peptides, 26:1972-7 (2005)) and decreased sexual response in females (U.S. Pat. No. 6,713,487 (Yu et al., 2004); and Fourcroy, J. L., Drugs, 63:1445-57 (2003)), diseases or conditions resulting from treatment or insult to the organism such as organ transplant rejection (U.S. Pat. No. 6,713,487 (Yu et al., 2004); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), ischemia and reperfusion injury (Mioni, C. et al., Euro. J. Pharm., 477:227-34 (2003); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), treatment of spinal cord injury and to accelerate wound healing (Sharma H. S. et al., Acta. Nerochir. Suppl., 86:399-405 (2003); Sharma H. S., Ann. N.Y. Acad. Sci., 1053: 407-21 (2005); and U.S. Pat. No. 6,525,019 (D'Amato, 2003)), as well as weight loss caused by chemotherapy, radiation therapy, temporary or permanent immobilization (Harris, R. B. et al., Physiol. Behav., 73:599-608 (2001)) or dialysis, cardiovascular diseases or conditions such as hemorrhagic shock (Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), cardiogenic shock (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), hypovolemic shock (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), cardiovascular disorders (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)) and cardiac cachexia (Markison, S. et al., Endocrinology, 146:2766-73 (2005)), pulmonary diseases or conditions such as acute respiratory distress syndrome (U.S. Pat. No. 6,350,430 (Dooley et al., 2002); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), chronic obstructive pulmonary disease (U.S. Pat. No. 6,713,487 (Yu et al., 2004)), asthma (U.S. Pat. No. 6,713,487 (Yu et al., 2004)) and pulmonary fibrosis, to enhance immune tolerance (Luger, T. A. et al., Pathobiology, 67:318-21 (1999)) and to combat assaults to the immune system such as those associated with certain allergies (U.S. Pat. No. 6,713,487 (Yu et al., 2004)) or organ transplant rejection (U.S. Pat. No. 6,713,487 (Yu et al., 2004)); and Catania, A. et al., Pharm. Rev., 56:1-29 (2004)), treatment of dermatological diseases and conditions such as psoriasis (U.S. Pat. No. 6,713,487 (Yu et al., 2004)), skin pigmentation depletion (U.S. Pat. No. 6,713,487 (Yu et al., 2004); and Ye, Z. et al., Peptides, 26:2017-25 (2005)), acne (Hatta, N. et al., J. Invest. Dermatol., 116:564-70 (2001); and Bohm, M. et al., J. Invest. Dermatol., 118:533-9 (2002)), keloid formation (U.S. Pat. No. 6,525,019 (D'Amato, 2003)) and skin cancer (Sturm, R. A., Melanoma Res., 12:405-16 (2002); and Bastiens, M. T. et al., Am. J. Hum. Genet., 68:884-94 (2001)), behavioral, central nervous system or neuronal conditions and disorders such as anxiety (U.S. Pat. No. 6,720,324 (Marzabadi et al., 2003); and Pontillo, J. et al., Bioorganic & Med. Chem. Ltrs., 15:2541-6 (2005)), depression (Chaki, S. et al., Peptides, 26:1952-64 (2005), Bednarek, M. A. et al., Expert Opinion Ther. Patents, 14:327-36 (2004); and U.S. Pat. No. 6,720,324 (Marzabadi et al., 2003)), memory and memory dysfunction (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); and Voisey, J. et al., Curr. Drug Targets, 4:586-97 (2003)), modulating pain perception (U.S. Pat. No. 6,613,874 (Mazur et al., 2003); Bertolini, A. et al., J. Endocrinol. Invest., 4:241-51 (1981); and Vrinten, D. et al., J. Neuroscience, 20:8131-7 (2000)) and treating neuropathic pain (Pontillo, J. et al., Bioorganic & Med. Chem. Ltrs., 15:2541-6 (2005)), conditions and diseases associated with alcohol consumption, alcohol abuse and/or alcoholism (WO 05/060985 (Marsh et al., 2005); and Navarro, M. et al., Alcohol Clin. Exp. Res., 29:949-57 (2005)), and renal conditions or diseases such as the treatment of renal cachexia (Markison, S. et al., Endocrinology, 146:2766-73 (2005)) or natriuresis (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)).
Ligand compounds activating one or more melanocortin receptor would be useful for modulating a wide variety of normalizing or homeostatic activities in a subject in need thereof including thyroxin release (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), aldosterone synthesis and release (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), body temperature (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), blood pressure (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), heart rate (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), vascular tone (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), brain blood flow (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), blood glucose levels (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), bone metabolism, bone formation or development (Dumont, L. M. et al., Peptides, 26:1929-35 (2005)), ovarian weight (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), placental development (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), prolactin and FSH secretion (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), intrauterine fetal growth (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), parturition (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), spermatogenesis (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), sebum and pheromone secretion (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), neuroprotection (U.S. Pat. No. 6,639,123 (Van der Ploeg et al., 2003)) and nerve growth (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)) as well as modulating motivation (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)), learning (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)) and other behaviors (U.S. Pat. No. 6,613,874 (Mazur et al., 2003)).
Hydantoin (C3H2N2O2), also known as glycolyl urea or by its IUPAC name imidazole-2,4(3H, 5H)-dione, is a crystalline, heterocyclic organic compound which can be thought of as a cyclic “double-condensation reaction” product of glycolic acid and urea or allantoin, an oxidation product (C4H6N4O3) of uric acid that is the metabolic end product of vertebrate purine oxidation. Hydantoin which has the following chemical structure:
and is similar to imidazolidine, the hydrogen-saturated analogue of imidazole except that it has carbonyl groups in the 2nd and 4th positions in the ring. It has a molecular weight of 100.076 g/mol, is slightly soluble in water and has a melting point of 216-224° C. Hydantoin and its derivatives have antibacterial, antifungal, antiprotozoal and anthelmintic properties. Hydantoin has traditionally been an ingredient in anticonvulsants used in the treatment of seizures associated with epilepsy. It is believed that hydantoins depress abnormal neuronal discharges in the central nervous system. Phenytoin, another anticonvulsant synthesized from hydantoin, is used as a skeletal muscle relaxant and for the treatment of severe trigeminal neuralgia.
Applicants have discovered a class of compounds that have a high affinity for the melanocortin receptors, particularly selective for the MC-4 subtype relative to the other receptor subtype, especially the MC-5 subtype. Specifically, Applicants discovered that peptides modified with hydantoin exhibited increased affinity for the MC-4 receptor subtype. It is therefore an objective of this invention to provide chemical compounds that activate or antagonize the MC-4 receptor subtype. It is a further an objective of the present invention to provide ligands for the melanocortin receptors which exhibit greater stability and selectivity for melanocortin receptors than native melanocortin receptor ligands. Yet another objective of the invention is to provide means for the administration of said compounds for the treatment of various ailments and/or conditions associated with either the over or the under production of melanocortin peptides.